7764221 has 2 divisors, whose sum is σ = 7764222. Its totient is φ = 7764220.

The previous prime is 7764193. The next prime is 7764247. The reversal of 7764221 is 1224677.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6832996 + 931225 = 2614^2 + 965^2 .

It is an emirp because it is prime and its reverse (1224677) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7764221 is a prime.

It is a nialpdrome in base 10.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (7763221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3882110 + 3882111.

It is an arithmetic number, because the mean of its divisors is an integer number (3882111).

Almost surely, 2^7764221 is an apocalyptic number.

It is an amenable number.

7764221 is a deficient number, since it is larger than the sum of its proper divisors (1).

7764221 is an equidigital number, since it uses as much as digits as its factorization.

7764221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4704, while the sum is 29.

The square root of 7764221 is about 2786.4351777854. The cubic root of 7764221 is about 198.0155499130.

Adding to 7764221 its reverse (1224677), we get a palindrome (8988898).

The spelling of 7764221 in words is "seven million, seven hundred sixty-four thousand, two hundred twenty-one".